Description: (Applicant's Description) Endocrinology is a discipline encompassing the control of growth and differentiated cellular function via the direct action of hormones or indirectly through hormonal stimulation of growth factors, cytokines, and chemokines. The goals of Program A.2, Endocrinology are to better understand normal endocrine processes and the aberrations of these functions that lead to uncontrolled cellular growth or diminished programmed cell death. The program is subdivided into four subprograms: 1. Endocrine Control of Growth and Differentiated Function 2. Endocrine Control of Hormone Synthesis and Secretion. 3. Cancer Survivors and 4. Hormonal Control of Carcinogenesis The first encompasses (a) the study of receptor mediated and growth factor function in breast cancer and (b) the regulation of these processes in health and in other tumors. The second involves the normal physiologic processes that regulate synthesis of prolactin, growth hormone, and gonadotropins. The third relates to survivorship issues in patients with breast cancer and with brain tumors. The fourth is an area of developing emphasis which examines the hypothesis that estrogen metabolites are genotoxic and can induce breast and potentially, prostate cancer.